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Refactor flush logic to avoid cache manager deadlocks #1

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142 changes: 87 additions & 55 deletions Ext4Fsd/ext3/generic.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -315,64 +315,96 @@ Ext2FlushRange(IN PEXT2_VCB Vcb, LARGE_INTEGER s, LARGE_INTEGER e)
NTSTATUS
Ext2FlushVcb(IN PEXT2_VCB Vcb)
{
LARGE_INTEGER s = {0}, o;
struct ext4_sb_info *sbi = &Vcb->sbi;
struct rb_node *node;
struct buffer_head *bh;

if (!IsFlagOn(Vcb->Flags, VCB_GD_LOADED)) {
CcFlushCache(&Vcb->SectionObject, NULL, 0, NULL);
goto errorout;
}

ASSERT(ExIsResourceAcquiredExclusiveLite(&Vcb->MainResource));

__try {

/* acqurie gd block */
ExAcquireResourceExclusiveLite(&Vcb->sbi.s_gd_lock, TRUE);

LARGE_INTEGER s = {0}, o;
struct rb_node *node;
struct buffer_head *bh;

typedef struct _EXT2_BUSY_RANGE {
LARGE_INTEGER Start;
ULONG Length;
} EXT2_BUSY_RANGE, *PEXT2_BUSY_RANGE;

PEXT2_BUSY_RANGE BusyRanges = NULL;
ULONG BusyCount = 0;
ULONG BusyIndex = 0;

if (!IsFlagOn(Vcb->Flags, VCB_GD_LOADED)) {
CcFlushCache(&Vcb->SectionObject, NULL, 0, NULL);
goto errorout;
}

__try {

/* acqurie gd block */
ExAcquireResourceExclusiveLite(&Vcb->sbi.s_gd_lock, TRUE);

/* acquire bd lock to avoid bh creation */
ExAcquireResourceExclusiveLite(&Vcb->bd.bd_bh_lock, TRUE);

/* drop unused bh */
Ext2DropBH(Vcb);

/* flush volume with all outstanding bh skipped */

node = rb_first(&Vcb->bd.bd_bh_root);
while (node) {

bh = container_of(node, struct buffer_head, b_rb_node);
node = rb_next(node);

o.QuadPart = bh->b_blocknr << BLOCK_BITS;
ASSERT(o.QuadPart >= s.QuadPart);

if (o.QuadPart == s.QuadPart) {
s.QuadPart = s.QuadPart + bh->b_size;
continue;
}

if (o.QuadPart > s.QuadPart) {
Ext2FlushRange(Vcb, s, o);
s.QuadPart = (bh->b_blocknr << BLOCK_BITS) + bh->b_size;
continue;
}
}

o = Vcb->PartitionInformation.PartitionLength;
Ext2FlushRange(Vcb, s, o);

} __finally {

ExReleaseResourceLite(&Vcb->bd.bd_bh_lock);
ExReleaseResourceLite(&Vcb->sbi.s_gd_lock);
}

errorout:
return STATUS_SUCCESS;
}
/* drop unused bh */
Ext2DropBH(Vcb);

/* count outstanding bh entries */
for (node = rb_first(&Vcb->bd.bd_bh_root);
node != NULL;
node = rb_next(node)) {
BusyCount++;
}

if (BusyCount) {
BusyRanges = Ext2AllocatePool(
PagedPool,
BusyCount * sizeof(EXT2_BUSY_RANGE),
'rF2E');
if (BusyRanges) {
for (node = rb_first(&Vcb->bd.bd_bh_root);
node != NULL && BusyIndex < BusyCount;
node = rb_next(node)) {

bh = container_of(node, struct buffer_head, b_rb_node);
BusyRanges[BusyIndex].Start.QuadPart = bh->b_blocknr << BLOCK_BITS;
BusyRanges[BusyIndex].Length = bh->b_size;
BusyIndex++;
}
} else {
BusyCount = 0;
}
}

} __finally {

ExReleaseResourceLite(&Vcb->bd.bd_bh_lock);
ExReleaseResourceLite(&Vcb->sbi.s_gd_lock);
}

s.QuadPart = 0;

if (BusyRanges && BusyIndex) {
ULONG i;
for (i = 0; i < BusyIndex; i++) {
o = BusyRanges[i].Start;
if (o.QuadPart > s.QuadPart) {
Ext2FlushRange(Vcb, s, o);
s.QuadPart = BusyRanges[i].Start.QuadPart + BusyRanges[i].Length;
} else {
LONGLONG BusyEnd = BusyRanges[i].Start.QuadPart + BusyRanges[i].Length;
if (BusyEnd > s.QuadPart) {
s.QuadPart = BusyEnd;
}
}
}
}

o = Vcb->PartitionInformation.PartitionLength;
Ext2FlushRange(Vcb, s, o);

if (BusyRanges) {
Ext2FreePool(BusyRanges, 'rF2E');
}

errorout:
return STATUS_SUCCESS;
}

BOOLEAN
Ext2SaveGroup(
Expand Down
121 changes: 77 additions & 44 deletions Ext4Fsd/flush.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -55,12 +55,14 @@ Ext2FlushFile (
IN PEXT2_CCB Ccb
)
{
IO_STATUS_BLOCK IoStatus = {0};

ASSERT(Fcb != NULL);
ASSERT((Fcb->Identifier.Type == EXT2FCB) &&
(Fcb->Identifier.Size == sizeof(EXT2_FCB)));

IO_STATUS_BLOCK IoStatus = {0};
SECTION_OBJECT_POINTERS *SectionObject = NULL;
BOOLEAN ResourceReleased = FALSE;

ASSERT(Fcb != NULL);
ASSERT((Fcb->Identifier.Type == EXT2FCB) &&
(Fcb->Identifier.Size == sizeof(EXT2_FCB)));

__try {

/* do nothing if target fie was deleted */
Expand All @@ -83,24 +85,36 @@ Ext2FlushFile (
}
}

if (IsDirectory(Fcb)) {
IoStatus.Status = STATUS_SUCCESS;
__leave;
}

DEBUG(DL_INF, ( "Ext2FlushFile: Flushing File Inode=%xh %S ...\n",
Fcb->Inode->i_ino, Fcb->Mcb->ShortName.Buffer));

CcFlushCache(&(Fcb->SectionObject), NULL, 0, &IoStatus);
ClearFlag(Fcb->Flags, FCB_FILE_MODIFIED);

} __finally {

/* do cleanup here */
}

return IoStatus.Status;
}
if (IsDirectory(Fcb)) {
IoStatus.Status = STATUS_SUCCESS;
__leave;
}

DEBUG(DL_INF, ( "Ext2FlushFile: Flushing File Inode=%xh %S ...\n",
Fcb->Inode->i_ino, Fcb->Mcb->ShortName.Buffer));

SectionObject = &Fcb->SectionObject;

ExReleaseResourceLite(&Fcb->MainResource);
ResourceReleased = TRUE;

CcFlushCache(SectionObject, NULL, 0, &IoStatus);

} __finally {

/* do cleanup here */

if (ResourceReleased) {
ExAcquireResourceExclusiveLite(&Fcb->MainResource, TRUE);

if (NT_SUCCESS(IoStatus.Status)) {
ClearFlag(Fcb->Flags, FCB_FILE_MODIFIED);
}
}
}

return IoStatus.Status;
}

NTSTATUS
Ext2FlushFiles(
Expand Down Expand Up @@ -153,7 +167,8 @@ Ext2Flush (IN PEXT2_IRP_CONTEXT IrpContext)

PDEVICE_OBJECT DeviceObject = NULL;

BOOLEAN MainResourceAcquired = FALSE;
BOOLEAN MainResourceAcquired = FALSE;
BOOLEAN VcbResourceReleased = FALSE;

__try {

Expand Down Expand Up @@ -202,22 +217,35 @@ Ext2Flush (IN PEXT2_IRP_CONTEXT IrpContext)
DEBUG(DL_INF, ("Ext2Flush-pre: total mcb records=%u\n",
FsRtlNumberOfRunsInLargeMcb(&Vcb->Extents)));

if (FcbOrVcb->Identifier.Type == EXT2VCB) {

Ext2VerifyVcb(IrpContext, Vcb);
Status = Ext2FlushFiles(IrpContext, (PEXT2_VCB)(FcbOrVcb), FALSE);
if (NT_SUCCESS(Status)) {
__leave;
}

/* TO INVESTIGATE: Ext2FlushFiles will always return STATUS_SUCCESS so Ext2FlushVolume will never be called? */

Status = Ext2FlushVolume(IrpContext, (PEXT2_VCB)(FcbOrVcb), FALSE);

if (NT_SUCCESS(Status) && IsFlagOn(Vcb->Volume->Flags, FO_FILE_MODIFIED)) {
ClearFlag(Vcb->Volume->Flags, FO_FILE_MODIFIED);
}

if (FcbOrVcb->Identifier.Type == EXT2VCB) {

Ext2VerifyVcb(IrpContext, Vcb);
ExReleaseResourceLite(&FcbOrVcb->MainResource);
VcbResourceReleased = TRUE;

Status = Ext2FlushFiles(IrpContext, (PEXT2_VCB)(FcbOrVcb), FALSE);

ExAcquireResourceExclusiveLite(&FcbOrVcb->MainResource, TRUE);
VcbResourceReleased = FALSE;

if (NT_SUCCESS(Status)) {
__leave;
}

/* TO INVESTIGATE: Ext2FlushFiles will always return STATUS_SUCCESS so Ext2FlushVolume will never be called? */

ExReleaseResourceLite(&FcbOrVcb->MainResource);
VcbResourceReleased = TRUE;

Status = Ext2FlushVolume(IrpContext, (PEXT2_VCB)(FcbOrVcb), FALSE);

ExAcquireResourceExclusiveLite(&FcbOrVcb->MainResource, TRUE);
VcbResourceReleased = FALSE;

if (NT_SUCCESS(Status) && IsFlagOn(Vcb->Volume->Flags, FO_FILE_MODIFIED)) {
ClearFlag(Vcb->Volume->Flags, FO_FILE_MODIFIED);
}

} else if (FcbOrVcb->Identifier.Type == EXT2FCB) {

Fcb = (PEXT2_FCB)(FcbOrVcb);
Expand All @@ -236,9 +264,14 @@ Ext2Flush (IN PEXT2_IRP_CONTEXT IrpContext)

} __finally {

if (MainResourceAcquired) {
ExReleaseResourceLite(&FcbOrVcb->MainResource);
}
if (VcbResourceReleased) {
ExAcquireResourceExclusiveLite(&FcbOrVcb->MainResource, TRUE);
VcbResourceReleased = FALSE;
}

if (MainResourceAcquired) {
ExReleaseResourceLite(&FcbOrVcb->MainResource);
}

if (!IrpContext->ExceptionInProgress) {

Expand Down
64 changes: 37 additions & 27 deletions Ext4Fsd/shutdown.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -60,33 +60,43 @@ Ext2ShutDown (IN PEXT2_IRP_CONTEXT IrpContext)

Vcb = CONTAINING_RECORD(ListEntry, EXT2_VCB, Next);

if (ExAcquireResourceExclusiveLite(
&Vcb->MainResource,
TRUE )) {

if (IsMounted(Vcb)) {

/* update fs write time */
KeQuerySystemTime(&SysTime);
Ext2TimeToSecondsSince1970(&SysTime, &LinuxTime.LowPart, &LinuxTime.HighPart);
Vcb->SuperBlock->s_wtime = LinuxTime.LowPart;
Vcb->SuperBlock->s_wtime_hi = (UCHAR)LinuxTime.HighPart;

/* update mount count */
Vcb->SuperBlock->s_mnt_count++;
Ext2SaveSuper(IrpContext, Vcb);

/* flush dirty cache for all files */
Ext2FlushFiles(IrpContext, Vcb, TRUE);

/* flush volume stream's cache to disk */
Ext2FlushVolume(IrpContext, Vcb, TRUE);

/* send shutdown request to underlying disk */
Ext2DiskShutDown(Vcb);
}

ExReleaseResourceLite(&Vcb->MainResource);
if (ExAcquireResourceExclusiveLite(
&Vcb->MainResource,
TRUE )) {

if (IsMounted(Vcb)) {

BOOLEAN VcbMainReleased = FALSE;

/* update fs write time */
KeQuerySystemTime(&SysTime);
Ext2TimeToSecondsSince1970(&SysTime, &LinuxTime.LowPart, &LinuxTime.HighPart);
Vcb->SuperBlock->s_wtime = LinuxTime.LowPart;
Vcb->SuperBlock->s_wtime_hi = (UCHAR)LinuxTime.HighPart;

/* update mount count */
Vcb->SuperBlock->s_mnt_count++;
Ext2SaveSuper(IrpContext, Vcb);

ExReleaseResourceLite(&Vcb->MainResource);
VcbMainReleased = TRUE;

/* flush dirty cache for all files */
Ext2FlushFiles(IrpContext, Vcb, TRUE);

/* flush volume stream's cache to disk */
Ext2FlushVolume(IrpContext, Vcb, TRUE);

if (VcbMainReleased) {
ExAcquireResourceExclusiveLite(&Vcb->MainResource, TRUE);
VcbMainReleased = FALSE;
}

/* send shutdown request to underlying disk */
Ext2DiskShutDown(Vcb);
}

ExReleaseResourceLite(&Vcb->MainResource);
}
}

Expand Down